Pregnancy Week & Due Date Calculator
Use this free tool to estimate how far along you are, your due date, and how many weeks remain.
What is a “how pregnant” calculator?
A how pregnant calculator estimates your gestational age (how far along you are in weeks and days) and your estimated due date. Most people use either the first day of their last menstrual period (LMP), a known conception date, or an existing due date to run the calculation.
These tools are useful for planning appointments, understanding trimester milestones, and tracking pregnancy progress. They are not a diagnosis and should not replace medical care.
How this calculator works
1) Last Menstrual Period (LMP) method
This is the most common method. Pregnancy is measured from the first day of your last period, not the day of conception. A standard pregnancy is estimated at 280 days (40 weeks) from LMP.
- Estimated due date = LMP + 280 days (adjusted for cycle length if entered)
- Gestational age = today - LMP
2) Conception date method
If you know the conception date, the calculator adds 266 days to estimate due date. Gestational age is then calculated as conception-based age plus two weeks, because medical dating starts before conception.
3) Due date method
If your provider already gave you a due date, this mode works backward to estimate current pregnancy week and likely LMP.
How accurate is a pregnancy calculator?
It is a strong estimate, especially with reliable dates. Still, every pregnancy is different. Ovulation timing, implantation timing, and cycle irregularity can shift actual age by several days.
Ultrasound measurements in early pregnancy are often the best way to confirm or refine dating. Your clinician may adjust your due date if ultrasound and menstrual dates differ significantly.
Understanding your results
- Gestational age: How far along you are in weeks and days.
- Estimated due date (EDD): The expected date around 40 weeks.
- Trimester: First, second, or third stage of pregnancy.
- Weeks remaining: Time left until the estimated due date.
Quick trimester guide
First trimester (0 to 13 weeks + 6 days)
Early development is rapid. Many people experience fatigue, nausea, breast tenderness, and appetite changes.
Second trimester (14 to 27 weeks + 6 days)
Energy often improves. Anatomy scans and routine prenatal checks become important milestones.
Third trimester (28 weeks to birth)
Baby growth accelerates. You may notice increased discomfort, sleep changes, and more frequent monitoring near term.
When to contact a healthcare professional
Use this calculator for education and planning, but contact your provider promptly for medical concerns. Seek care urgently for severe pain, heavy bleeding, fainting, persistent vomiting, fever, or any symptom that feels alarming.
Frequently asked questions
Is conception date the same as gestational age start?
No. Clinical pregnancy dating starts about two weeks before conception, from LMP.
What if I have irregular cycles?
Enter your average cycle length for a better estimate, then confirm with prenatal care and ultrasound.
Can due date change?
Yes. Your clinician may revise your estimated due date based on ultrasound findings and clinical history.
Bottom line
A how pregnant calculator is a practical way to estimate your current week of pregnancy and due date in seconds. Use it as a planning tool, then partner with your healthcare team for personalized and accurate prenatal guidance.